Push rods of pistons used in vehicle brake applications are pushed into the cylinder by the actuating force of the operating person and returned into their starting position by return springs. In this context, two return springs are provided, one of which is positioned within the piston and acts directly on the piston while the other one is fixed outside the piston and returns the brake pedal into its starting position.
In master cylinders it may happen that the external spring extracts the piston rod out of the piston. To prevent separation of the rod and piston various approaches have been taken such as clips. All of these known solutions share a common drawback in of steel, retaining members in the shape of rubber rings, and undercuts in the piston in respect of the piston rod, which are formed, for example, by caulking that the known securing means do not suffice in many cases to prevent the piston rod from being moved out in the event of a sudden release of the actuating pedal. In many cases the solutions which have become state of the art are, furthermore, difficult to assemble insofar as they require additional operations when the piston rod is attached to the piston. Many times the prior-art solutions are, moreover, dependent in their securing action on the angular position the piston rod assumes at each moment in respect of the longitudinal axis of the piston.
An object of the present invention is to create an inexpensive securing means which reliably latches the rod within the piston and resists sizable extracting forces (independent of the angular position of the piston rod).